Personal pagers are small battery powered devices worn by individuals so that messages can be transmitted to them by radio frequency from a remote message sender. The currently available pagers are of two general categories. Numeric only pagers are capable of receiving only a single type of message, i.e. a numeric message, which is typically the telephone number of the person sending a message to the person being paged.
Alphanumeric pagers, by contrast, permit the transmission of both language as well as numeric information, and thus permit the transmission of short messages to an individual being paged. Both pagers rely on a network of radio transmitters and particularized identification codes, referred to as CAP CODES so that each particular individual who is wearing a pager can be identified when a page is intended for that individual.
Paging systems operate on the basis of a paging center which transmits out coded information, on an assigned radio frequency, to all of the pagers associated with that system. The particular personal pager which has its CAP CODE identified in any particular transmission is the only one that receives and displays that transmission. If a system is operated by a central dispatcher, which is the only one sending paging messages to the various pagers in the field, it is not a particular problem to devise a method for the input of the numeric or text information into the paging system. However, when paging services are offered to the public at large, and large and small businesses broadly, the methods by which paging information or messages are provided as inputs to the alphanumeric system becomes a greater logistical and technical problem.
For numeric pagers, the input of numeric information to the paging system is a relatively straight forward operation. A user dials the paging system which is typically operated by a robotic or computer controlled device. The system device tells the user, with appropriate computerized voice cues, to enter the information as to the PIN of the person to be paged and the numeric message to be sent in the page message, with the user entering that information by pressing numbers on his or her telephone dial pad. The tones generated by a touch tone telephone, known as DTMF, can convey numeric information to the paging station, which can then transmit the page message to the desired individual.
With alphanumeric paging systems, the process is a little more complicated because of the demands of entering text data at remote locations. One type of system utilizes a live operator who answers a call in voice and then receives the message verbally over the telephone line from the remote caller. The operator then enters the text information into a keyboard associated with the paging transmission unit, and the page is properly formatted and sent to its intended recipient. However, this method is relatively expensive, in that it requires a system of stand-by operators available at all times, and does not provide the speed and privacy that many users would like in an alphanumeric paging system.
Current alphanumeric paging systems accept textual information from remote data entry points using a common protocol. One such protocol, known as the telocator alphanumeric protocol (or TAP), was designed to facilitate transmission from computer to computer of the input information for alphanumeric paging systems. In one sense, the protocol is not a communication protocol, since it relies on conventional computer to computer modem communications. Any of several modem protocols may be used for the actual electronic protocol. For example, the current TAP protocol recommends that a Bell 103 compatible modem be used to transmit 300 Baud information. Other speeds or modem types can be used as appropriate.
As usual, all such modems operating under standard ASCII or CCITT protocols for computer transmission of information require handshakes, both send and receive capability, and full duplex capability. The TAP protocol is intended to define within the transmission from a remote computer or digital facility to a paging terminal how the data internally in the packet is characterized so that the receiving terminal can recognize the PIN and identify the message to be transmitted to the individual to be paged. Other alphanumeric paging entry protocols are also in common use, all of which are also based on standard computer communication methods.
The availability of TAP-based alphanumeric paging terminals allows users with remote computers to input alphanumeric paging messages to be transmitted by the paging system. While this expands the network of available senders of an alphanumeric paging message, it still requires the expense and often the bulk of a computer, or at least a device with full duplex handshake modems, with specific software, in order to properly enter alphanumeric information into the system.